---
description:
  Learn about reactive variables in Apollo Client 3, a useful mechanism for storing local state
  outside the cache. Modify them anywhere & trigger updates in active queries.
---

# Reactive Variables

New in Apollo Client 3, reactive variables are a useful mechanism for storing local state outside
the Apollo Client cache. Because they're separate from the cache, reactive variables can store data
of any type and structure, and you can interact with them anywhere in your application without using
GraphQL syntax.

Most importantly, modifying a reactive variable automatically triggers an update of every active
query that depends on that variable. A query depends on a reactive variable if any of the query's
requested fields defines a read function that reads the variable's value.

Please read the
["Reactive variables"](https://apollographql.com/docs/react/local-state/reactive-variables) chapter
on Apollo Client documentation.
